EP3833879B1 - Method for temporarily releasing screw anchorage - Google Patents
Method for temporarily releasing screw anchorage Download PDFInfo
- Publication number
- EP3833879B1 EP3833879B1 EP19745144.6A EP19745144A EP3833879B1 EP 3833879 B1 EP3833879 B1 EP 3833879B1 EP 19745144 A EP19745144 A EP 19745144A EP 3833879 B1 EP3833879 B1 EP 3833879B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- screw
- hole
- retrofitting
- thread
- substrate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000000034 method Methods 0.000 title claims description 23
- 238000009420 retrofitting Methods 0.000 claims description 65
- 239000000758 substrate Substances 0.000 claims description 51
- 239000011440 grout Substances 0.000 claims description 41
- 230000013011 mating Effects 0.000 claims description 13
- 229910052500 inorganic mineral Inorganic materials 0.000 claims description 11
- 239000011707 mineral Substances 0.000 claims description 11
- 239000000428 dust Substances 0.000 description 19
- 239000004567 concrete Substances 0.000 description 13
- 238000010079 rubber tapping Methods 0.000 description 13
- 238000009434 installation Methods 0.000 description 5
- 238000003780 insertion Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 230000037431 insertion Effects 0.000 description 3
- 239000004570 mortar (masonry) Substances 0.000 description 3
- 230000010006 flight Effects 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000008092 positive effect Effects 0.000 description 2
- 239000004593 Epoxy Substances 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 239000004035 construction material Substances 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 238000011900 installation process Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Images
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
- F16B25/00—Screws that cut thread in the body into which they are screwed, e.g. wood screws
- F16B25/001—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by the material of the body into which the screw is screwed
- F16B25/0026—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by the material of the body into which the screw is screwed the material being a hard non-organic material, e.g. stone, concrete or drywall
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
- F16B13/00—Dowels or other devices fastened in walls or the like by inserting them in holes made therein for that purpose
- F16B13/14—Non-metallic plugs or sleeves; Use of liquid, loose solid or kneadable material therefor
- F16B13/141—Fixing plugs in holes by the use of settable material
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/49826—Assembling or joining
- Y10T29/49947—Assembling or joining by applying separate fastener
- Y10T29/49966—Assembling or joining by applying separate fastener with supplemental joining
Definitions
- the invention relates to a method for temporarily releasing a screw anchorage.
- EP0955476 B2 discloses a fixing arrangement in a concrete substrate, including a tapping screw arranged in a hole, wherein the hole is so filled with a hardenable grout that an annular gap between the wall of the hole and the screw is completely filled with the grout and, when the grout has hardened, the thread of the screw is embedded partly in the substrate and partly in the shell of grout.
- US2010247267 A1 proposes specific concrete screw shaft diameters, in relation to the diameter of the drill for making the hole in which the screw is to be placed.
- a grout can be optionally used.
- WO17025318 A1 describes a method for installing a concrete screw in concrete, in which a preliminary tread is cut in a first step and subsequently, the concrete screw is screwed into this preliminary thread, thereby widening the preliminary thread.
- DE102011003127 A1 describes a glass cartridge containing a hardenable grout, wherein the glass cartridge is provided with a mechanical holding part, which is designed as a retaining spring. The cartridge is placed in a borehole and a screw is subsequently screwed in, thereby opening the cartridge.
- US2017138390 A1 discloses a system for dispensing hardenable grout when a screw is screwed into a concrete borehole.
- US5730557 A describes a mortar mixture unit for chemical attachment of anchors in holes, which includes an essentially cylindrical container, which can be ruptured when inserting the anchor into the hole.
- hardenable grout is only applied when the screw anchorage is re-installed, but not in the initial installation process.
- anchorage performance might not be as good as before anymore.
- this performance drop can, at least partly, be related to substrate dust.
- Substrate dust in particular concrete dust, arises when a tapping screw is screwed tappingly into a hole and when the screw cuts on the hole wall.
- Arising substrate dust can then collect between the lateral wall of the screw and the lateral wall of the hole and here, it can positively modified stress states in the surroundings of the screw, thereby improving anchorage performance, as described in US2010247267 A1 .
- the invention proposes to use grout when the - originally ungrouted - screw anchorage is re-established.
- the primary screw can have a shaft, and a drive for imparting torque on the shaft, wherein the drive can for example be a hex head.
- the shaft defines a longitudinal axis of the primary screw, which longitudinal axis extends in the direction of insertion of the primary screw.
- the thread of the primary screw is provided on the shaft of the primary screw and winds around the shaft and the longitudinal axis of the primary screw.
- the thread of the primary screw can have one or more thread flights.
- the thread of the primary screw is tappingly engaged in a mating thread, which implies that the thread is located in a mating thread which has been, at least partly, cut by the thread itself.
- the primary screw is located in an ungrouted hole, i.e. in a hole that is not provided with a grout liner.
- the primary screw is a tapping screw.
- the retrofitting screw can have a shaft, and a drive for imparting torque on the shaft, wherein the drive can for example be a hex head.
- the shaft defines a longitudinal axis of the retrofitting screw, which longitudinal axis extends in the direction of insertion of the retrofitting screw.
- the thread of the retrofitting screw is provided on the shaft of the retrofitting screw and winds around the shaft and the longitudinal axis of the retrofitting screw.
- the thread of the retrofitting screw can have one or more thread flights.
- the retrofitting screw can also be a tapping screw,
- the annular gap formed between the retrofitting screw and the substrate when screwing in the retrofitting screw can be understood to be the space located between the lateral surface of the retrofitting screw, in particular between the lateral surface of the shaft of the retrofitting screw, and the lateral surface of the hole.
- the annular gap can form a continuous annulus or it can also form a discontinuous, interrupted annulus, for example when the shaft of the retrofitting screw touches the wall of the hole, in particular when the shaft is not exactly centred in the hole or when the hole is not exactly cylindrical.
- the annular gap is formed as a consequence of screwing the retrofitting screw into the hole and/or while screwing the retrofitting screw into the hole. In particular, the retrofitting screw is screwed into the hole and in doing so, the annular gap is formed between the retrofitting screw and the substrate.
- the grout comprises a hardenable mass and can for example be epoxy-based or cement-based.
- the grout can preferably be a mortar.
- hardening of the hardenable grout in the annular gap can be performed by allowing curing time of the grout to lapse.
- the substrate comprises mineral construction material. It is particularly preferred that the mineral substrate is a concrete substrate, since in concrete, the described positive effect of substrate dust, concrete dust in this case, can be particularly significant.
- the substrate can also be a masonry substrate.
- the retrofitting screw and the primary screw have same thread pitch and/or same thread core diameter. Due to this geometric resemblance, particularly easy re-installation is possible and a particular good load behaviour of the retrofitting screw can be obtained.
- the retrofitting screw can be a used screw, in particular a tappingly-used screw, i.e. a screw that has been tapped into a mineral substrate, in particular a concrete substrate, before. Due to the stabilizing effect of the grout, the retrofitting screw can have a worn thread before it is screwed into the hole in the inventive method.
- the primary screw and the retrofitting screw are preferably of the same type.
- a screw that has been previously used in a neighbouring attachment point can be used as retrofitting screw.
- Being of the same type can imply that both screws, within usual manufacturing and wear tolerances, have the same shape and/or material composition.
- the retrofitting screw and the primary screw are one and the same, i.e. if both screws are identical.
- the primary screw that has been removed from the hole is subsequently screwed back into the hole, thereby forming the annular gap between the screw and the substrate.
- the same screw that has been previously removed screwingly from the ungrouted hole is screwingly re-inserting into the hole, and only in connection with the re-insertion, the annular gap surrounding the screw in the hole is filled with hardenable grout, which is then hardened.
- the thread of the retrofitting screw is screwed into the mating thread, in particular screwed into screw engagement with the mating thread.
- the retrofitting screw when the retrofitting screw is screwed in, its thread follows the already-available mating thread. This can allow particularly efficient re-installation without compromising on performance, since the effect of substrate dust is emulated by the grout after re-installation, and therefore, no tapping action for producing substrate dust is required during re-installation.
- a quantity of hardenable grout is placed in the hole before the retrofitting screw is screwed into the hole, and at least a fractional amount of this quantity of hardenable grout is subsequently placed in the annular gap.
- the quantity of hardenable grout can for example be located in a cartridge that is inserted into the hole, or the quantity can be injected into the hole using a dispenser.
- the retrofitting screw When the retrofitting screw is screwed into the hole, it can displace at least a fractional amount of the quantity into the annular gap, in particular by piston action exerted by the retrofitting screw.
- the hole can be a blind hole, which can facilitate displacement action of the retrofitting screw.
- the annular gap can be filled only partially or filled completely with hardenable grout.
- the ratio of the outer diameter of the thread of the primary screw to the pitch of the thread of the primary screw can be between 1 and 2, especially between 1.2 and 1.45. These are typical thread dimensions for screws that are intended for tapping insertion into mineral substrates, e.g. concrete or masonry substrates.
- the pitch can be understood to be the axial distance between successive turns of a thread flight.
- the ratio of the outer diameter of the thread of the retrofitting screw to the pitch of the thread of the retrofitting screw can be between 1 and 2, especially between 1.2 and 1.45
- Figures 1 to 2 show, in side view, consecutive steps of an example of a method for installing a primary screw in a hole in a mineral substrate, thereby providing an anchorage of an attachment part on the substrate.
- a hole 90 is provided in a substrate 6.
- the substrate 6 is a mineral substrate, preferably a concrete substrate, and the hole 90 can be a blind hole, that can for example be provided by drilling.
- An attachment part 4 is arranged at the surface of the substrate 6 surrounding the hole 90, so that an opening in the attachment part 4 is aligned with the hole 90.
- a primary screw 10 is then provided, which has a shaft 12 defining a longitudinal axis 99, and a thread 13 arranged on the shaft 12 and helically surrounding the shaft 12 and the longitudinal axis 99.
- the primary screw 10 is a tapping screw, which means that the primary screw 10, in particular its thread 13, is able to cut the substrate 6 and to form a mating thread 63 in the substrate 6.
- the primary screw 10 has a drive for imparting screw torque on the primary screw 10.
- the drive is a head 11, in particular a hex-head.
- the primary screw 10 can have one or more cutting edges 19, provided on the shaft 12 near the tip of the primary screw 10, for reaming the hole 90.
- the primary screw 10 is screwed into the hole 90, rotating around the longitudinal axis 99, and in this connection, the thread 13 of the primary screw 10 forms a mating thread 63 in the substrate 6, namely in the lateral wall of the hole 90. Due to this tapping action of the thread 13, and, if present, also due to the reaming action of the cutting edges 19, substrate dust 66 arises between the lateral surface of the shaft 12 and the cylindrical lateral wall of the hole 90. The substrate dust 66 located between the respective lateral surfaces can contribute to the performance of the primary screw 10, for example by providing lateral support of the shaft 12 in the hole 90.
- the primary screw 10 is screwed into the hole 90 until the head 11 of the primary screw 10, directly or via for example a washer, abuts on the attachment part 4, resulting in the configuration shown in figure 2 .
- Figures 3 to 5 show, in side view, consecutive steps of an example of an inventive method for temporarily releasing screw anchorage of the attachment part.
- the primary screw 10 is unscrewed from the hole 90, so that the thread 13 loses engagement with the mating thread 63, and the primary screw 10 is then removed from the hole 90. Anchorage previously provided by the primary screw 10 is thereby released, and it is now for example possible the remove the attachment part 4 from the substrate 6 and/or to relocate the attachment part 4.
- substrate dust 66 formerly located around the shaft 12 falls down and relocates, as schematically shown in figure 3 .
- the primary screw 10 was now simply screwed back into the hole 90, in order to restore anchorage, the positive effect of the substrate dust 66 would be, at least partly, lacking.
- a quantity 25 of hardenable grout 20 is placed in the hole 90. This can for example be done by injecting grout 20 into the hole 90 using a dispenser or by placing a cartridge containing grout 20 in the hole 90.
- the hardenable grout 20 can be a two component hardenable grout.
- the hardenable grout 20 can be a mortar.
- a retrofitting screw 30 which has a shaft 32 defining a longitudinal axis 98, and a thread 33 arranged on the shaft 32 and helically surrounding the shaft 32 and the longitudinal axis 98.
- the retrofitting screw 30 has a drive for imparting screw torque on the retrofitting screw 30.
- the drive is a head 31, in particular a hex-head.
- the retrofitting screw 30 can have one or more cutting edges 39, provided on the shaft 32 near the tip of the retrofitting screw 30.
- the retrofitting screw 30 is a tapping screw, which means that the retrofitting screw 30, in particular its thread 33, is able to cut the substrate 6 and to form a mating thread in the substrate 6.
- the retrofitting screw 30 is of the same type as the primary screw 10.
- the retrofitting screw 30 that is used here has been tappingly used before and therefore, its thread 33 is worn.
- the retrofitting screw 30 and the primary screw 10 are identical, i.e. the retrofitting screw 30 is the same as the primary screw 10 that has been previously removed from the hole 90.
- the retrofitting screw 30 (which is the primary screw 10) is screwed into the hole 90, thereby re-engaging the mating thread 63 of the hole 90 with the thread 33 of the retrofitting screw 30.
- the retrofitting screw 30 As the retrofitting screw 30 is lowered into the hole 90, it displaces hardenable grout 20, causing hardenable grout 20 to flow alongside the shaft 32 of the retrofitting screw 30 towards the mouth of the hole 90 into the annular gap 36 that arises between the shaft 32 of the retrofitting screw 30 and the wall of the hole 90.
- the hardenable grout 20 forms a liner 22, covering the wall of the hole 90.
- the retrofitting screw 30 is screwed into the hole 90 until the head 31 of the retrofitting screw 30, directly or via for example a washer, abuts on the attachment part 4, resulting in the configuration shown in figure 5 .
- the hardenable grout 20 located in the annular gap 36 is allowed to harden.
- the liner 22 made up of now hardened grout 20 can now improve anchorage performance in a similar way the substrate dust 66 did before, so that the hardened grout 20 located in the annular gap 36 can substitute or possibly even overcompensate the effect of the now missing substrate dust 66.
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Working Measures On Existing Buildindgs (AREA)
- Dowels (AREA)
Description
- The invention relates to a method for temporarily releasing a screw anchorage.
-
EP0955476 B2 discloses a fixing arrangement in a concrete substrate, including a tapping screw arranged in a hole, wherein the hole is so filled with a hardenable grout that an annular gap between the wall of the hole and the screw is completely filled with the grout and, when the grout has hardened, the thread of the screw is embedded partly in the substrate and partly in the shell of grout. -
US2010247267 A1 proposes specific concrete screw shaft diameters, in relation to the diameter of the drill for making the hole in which the screw is to be placed. A grout can be optionally used. -
WO17025318 A1 -
DE102011003127 A1 describes a glass cartridge containing a hardenable grout, wherein the glass cartridge is provided with a mechanical holding part, which is designed as a retaining spring. The cartridge is placed in a borehole and a screw is subsequently screwed in, thereby opening the cartridge. -
US2017138390 A1 discloses a system for dispensing hardenable grout when a screw is screwed into a concrete borehole. -
US5730557 A describes a mortar mixture unit for chemical attachment of anchors in holes, which includes an essentially cylindrical container, which can be ruptured when inserting the anchor into the hole. - It is an object of the invention to provide a method for temporarily releasing a tapping screw anchorage which, whilst being easy and reliably to perform, provides particularly good and continuous anchor performance.
- This object is achieved by a method according to claim 1. Dependent claims refer to preferred embodiments of the invention.
- According to the invention, there is provided a method for temporarily releasing a screw anchorage, in which
- a primary screw having a thread that is tappingly engaged in a mating thread in an ungrouted hole in a mineral substrate is unscrewed and removed from the hole,
- a retrofitting screw is subsequently screwed into the hole, thereby forming an annular gap between the retrofitting screw and the substrate, and
- hardenable grout is placed in the annular gap, and the hardenable grout is hardened in the annular gap.
- Thus, according to the invention, hardenable grout is only applied when the screw anchorage is re-installed, but not in the initial installation process.
- It is sometimes desirable that the anchorage provided by a tapping screw tapped into a mineral substrate is released and then re-established, for example if the part attached by the tapping screw is to be relocated or replaced. It was, however, found that when a tapping screw is unscrewed and subsequently the same screw or a same type screw is screwed back into the hole, anchorage performance might not be as good as before anymore. In connection with the invention, it was, surprisingly, found that this performance drop can, at least partly, be related to substrate dust. Substrate dust, in particular concrete dust, arises when a tapping screw is screwed tappingly into a hole and when the screw cuts on the hole wall. Arising substrate dust can then collect between the lateral wall of the screw and the lateral wall of the hole and here, it can positively modified stress states in the surroundings of the screw, thereby improving anchorage performance, as described in
US2010247267 A1 . In connection with the invention, it was realised that when the screw is unscrewed, the original substrate dust will usually relocate, and no significant fresh substrate dust will be produced when the same or a similar type screw is screwed back in, resulting in the anchorage now performing differently as compared to the original installation. Based on this surprising finding, the invention proposes to use grout when the - originally ungrouted - screw anchorage is re-established. This is based on the reasoning that, once the grout is hardened, it is able to emulate the presence of substrate dust in the annular gap that is formed between the retrofitting screw and the substrate, thereby compensating or even overcompensating potential anchorage performance loss due to substrate dust relocation. - The primary screw can have a shaft, and a drive for imparting torque on the shaft, wherein the drive can for example be a hex head. The shaft defines a longitudinal axis of the primary screw, which longitudinal axis extends in the direction of insertion of the primary screw. The thread of the primary screw is provided on the shaft of the primary screw and winds around the shaft and the longitudinal axis of the primary screw. The thread of the primary screw can have one or more thread flights. At the beginning of the method, the thread of the primary screw is tappingly engaged in a mating thread, which implies that the thread is located in a mating thread which has been, at least partly, cut by the thread itself. At the beginning of the method, the primary screw is located in an ungrouted hole, i.e. in a hole that is not provided with a grout liner. The primary screw is a tapping screw.
- The retrofitting screw can have a shaft, and a drive for imparting torque on the shaft, wherein the drive can for example be a hex head. The shaft defines a longitudinal axis of the retrofitting screw, which longitudinal axis extends in the direction of insertion of the retrofitting screw. The thread of the retrofitting screw is provided on the shaft of the retrofitting screw and winds around the shaft and the longitudinal axis of the retrofitting screw. The thread of the retrofitting screw can have one or more thread flights. The retrofitting screw can also be a tapping screw,
- The annular gap formed between the retrofitting screw and the substrate when screwing in the retrofitting screw can be understood to be the space located between the lateral surface of the retrofitting screw, in particular between the lateral surface of the shaft of the retrofitting screw, and the lateral surface of the hole. The annular gap can form a continuous annulus or it can also form a discontinuous, interrupted annulus, for example when the shaft of the retrofitting screw touches the wall of the hole, in particular when the shaft is not exactly centred in the hole or when the hole is not exactly cylindrical. The annular gap is formed as a consequence of screwing the retrofitting screw into the hole and/or while screwing the retrofitting screw into the hole. In particular, the retrofitting screw is screwed into the hole and in doing so, the annular gap is formed between the retrofitting screw and the substrate.
- The grout comprises a hardenable mass and can for example be epoxy-based or cement-based. The grout can preferably be a mortar. In a simple embodiment, hardening of the hardenable grout in the annular gap can be performed by allowing curing time of the grout to lapse. Being mineral, the substrate comprises mineral construction material. It is particularly preferred that the mineral substrate is a concrete substrate, since in concrete, the described positive effect of substrate dust, concrete dust in this case, can be particularly significant. The substrate can also be a masonry substrate.
- Preferably, the retrofitting screw and the primary screw have same thread pitch and/or same thread core diameter. Due to this geometric resemblance, particularly easy re-installation is possible and a particular good load behaviour of the retrofitting screw can be obtained.
- The retrofitting screw can be a used screw, in particular a tappingly-used screw, i.e. a screw that has been tapped into a mineral substrate, in particular a concrete substrate, before. Due to the stabilizing effect of the grout, the retrofitting screw can have a worn thread before it is screwed into the hole in the inventive method.
- The primary screw and the retrofitting screw are preferably of the same type. For example, a screw that has been previously used in a neighbouring attachment point can be used as retrofitting screw. Being of the same type can imply that both screws, within usual manufacturing and wear tolerances, have the same shape and/or material composition.
- It is particularly advantageous if the retrofitting screw and the primary screw are one and the same, i.e. if both screws are identical. Thus, the primary screw that has been removed from the hole is subsequently screwed back into the hole, thereby forming the annular gap between the screw and the substrate. In particular, the same screw that has been previously removed screwingly from the ungrouted hole is screwingly re-inserting into the hole, and only in connection with the re-insertion, the annular gap surrounding the screw in the hole is filled with hardenable grout, which is then hardened.
- It is particularly preferred that, when the retrofitting screw is screwed into the hole, the thread of the retrofitting screw is screwed into the mating thread, in particular screwed into screw engagement with the mating thread. Thus, when the retrofitting screw is screwed in, its thread follows the already-available mating thread. This can allow particularly efficient re-installation without compromising on performance, since the effect of substrate dust is emulated by the grout after re-installation, and therefore, no tapping action for producing substrate dust is required during re-installation.
- According to another preferred embodiment of the invention, a quantity of hardenable grout is placed in the hole before the retrofitting screw is screwed into the hole, and at least a fractional amount of this quantity of hardenable grout is subsequently placed in the annular gap.
- The quantity of hardenable grout can for example be located in a cartridge that is inserted into the hole, or the quantity can be injected into the hole using a dispenser. When the retrofitting screw is screwed into the hole, it can displace at least a fractional amount of the quantity into the annular gap, in particular by piston action exerted by the retrofitting screw. Advantageously, the hole can be a blind hole, which can facilitate displacement action of the retrofitting screw.
- The annular gap can be filled only partially or filled completely with hardenable grout.
- The ratio of the outer diameter of the thread of the primary screw to the pitch of the thread of the primary screw can be between 1 and 2, especially between 1.2 and 1.45. These are typical thread dimensions for screws that are intended for tapping insertion into mineral substrates, e.g. concrete or masonry substrates. In particular, and in line with the usual definition, the pitch can be understood to be the axial distance between successive turns of a thread flight.
- For the same reason, the ratio of the outer diameter of the thread of the retrofitting screw to the pitch of the thread of the retrofitting screw can be between 1 and 2, especially between 1.2 and 1.45
- The invention is explained in greater detail below with reference to preferred exemplary embodiments, which are depicted schematically in the accompanying drawings, wherein individual features of the exemplary embodiments presented below can be implemented either individually or in any combination within the scope of the present invention.
- Figures 1 to 2:
- consecutive steps of an example of a method for installing a primary screw in a hole in a mineral substrate; and
- Figures 3 to 5
- consecutive steps of an example of an inventive method for temporarily releasing an anchorage that has been previously provided by the method of
figures 1 and 2 . -
Figures 1 to 2 show, in side view, consecutive steps of an example of a method for installing a primary screw in a hole in a mineral substrate, thereby providing an anchorage of an attachment part on the substrate. - First, and as shown in
figure 1 , ahole 90 is provided in asubstrate 6. Thesubstrate 6 is a mineral substrate, preferably a concrete substrate, and thehole 90 can be a blind hole, that can for example be provided by drilling. Anattachment part 4 is arranged at the surface of thesubstrate 6 surrounding thehole 90, so that an opening in theattachment part 4 is aligned with thehole 90. - A
primary screw 10 is then provided, which has ashaft 12 defining alongitudinal axis 99, and athread 13 arranged on theshaft 12 and helically surrounding theshaft 12 and thelongitudinal axis 99. Theprimary screw 10 is a tapping screw, which means that theprimary screw 10, in particular itsthread 13, is able to cut thesubstrate 6 and to form amating thread 63 in thesubstrate 6. Theprimary screw 10 has a drive for imparting screw torque on theprimary screw 10. In the present case, the drive is ahead 11, in particular a hex-head. - The
primary screw 10 can have one ormore cutting edges 19, provided on theshaft 12 near the tip of theprimary screw 10, for reaming thehole 90. - The
primary screw 10 is screwed into thehole 90, rotating around thelongitudinal axis 99, and in this connection, thethread 13 of theprimary screw 10 forms amating thread 63 in thesubstrate 6, namely in the lateral wall of thehole 90. Due to this tapping action of thethread 13, and, if present, also due to the reaming action of the cutting edges 19,substrate dust 66 arises between the lateral surface of theshaft 12 and the cylindrical lateral wall of thehole 90. Thesubstrate dust 66 located between the respective lateral surfaces can contribute to the performance of theprimary screw 10, for example by providing lateral support of theshaft 12 in thehole 90. - The
primary screw 10 is screwed into thehole 90 until thehead 11 of theprimary screw 10, directly or via for example a washer, abuts on theattachment part 4, resulting in the configuration shown infigure 2 . -
Figures 3 to 5 show, in side view, consecutive steps of an example of an inventive method for temporarily releasing screw anchorage of the attachment part. - First, and as shown in
figure 3 , theprimary screw 10 is unscrewed from thehole 90, so that thethread 13 loses engagement with themating thread 63, and theprimary screw 10 is then removed from thehole 90. Anchorage previously provided by theprimary screw 10 is thereby released, and it is now for example possible the remove theattachment part 4 from thesubstrate 6 and/or to relocate theattachment part 4. - As the
primary screw 10 is unscrewed,substrate dust 66 formerly located around theshaft 12 falls down and relocates, as schematically shown infigure 3 . Thus, if theprimary screw 10 was now simply screwed back into thehole 90, in order to restore anchorage, the positive effect of thesubstrate dust 66 would be, at least partly, lacking. - In view of this, effect of
substrate dust 66 is emulated by hardenable grout 20 when anchorage is restored. In particular, and as shown infigure 4 , aquantity 25 of hardenable grout 20 is placed in thehole 90. This can for example be done by injecting grout 20 into thehole 90 using a dispenser or by placing a cartridge containing grout 20 in thehole 90. In particular if a cartridge is used, the hardenable grout 20 can be a two component hardenable grout. In particular, the hardenable grout 20 can be a mortar. - Subsequently, and as shown in
figure 5 , a retrofitting screw 30 is provided, which has ashaft 32 defining alongitudinal axis 98, and athread 33 arranged on theshaft 32 and helically surrounding theshaft 32 and thelongitudinal axis 98. The retrofitting screw 30 has a drive for imparting screw torque on the retrofitting screw 30. In the present case, the drive is ahead 31, in particular a hex-head. The retrofitting screw 30 can have one ormore cutting edges 39, provided on theshaft 32 near the tip of the retrofitting screw 30. The retrofitting screw 30 is a tapping screw, which means that the retrofitting screw 30, in particular itsthread 33, is able to cut thesubstrate 6 and to form a mating thread in thesubstrate 6. The retrofitting screw 30 is of the same type as theprimary screw 10. - The retrofitting screw 30 that is used here has been tappingly used before and therefore, its
thread 33 is worn. In this example, the retrofitting screw 30 and theprimary screw 10 are identical, i.e. the retrofitting screw 30 is the same as theprimary screw 10 that has been previously removed from thehole 90. - The retrofitting screw 30 (which is the primary screw 10) is screwed into the
hole 90, thereby re-engaging themating thread 63 of thehole 90 with thethread 33 of the retrofitting screw 30. As the retrofitting screw 30 is lowered into thehole 90, it displaces hardenable grout 20, causing hardenable grout 20 to flow alongside theshaft 32 of the retrofitting screw 30 towards the mouth of thehole 90 into the annular gap 36 that arises between theshaft 32 of the retrofitting screw 30 and the wall of thehole 90. In the annular gap 36, the hardenable grout 20 forms a liner 22, covering the wall of thehole 90. The retrofitting screw 30 is screwed into thehole 90 until thehead 31 of the retrofitting screw 30, directly or via for example a washer, abuts on theattachment part 4, resulting in the configuration shown infigure 5 . - The hardenable grout 20 located in the annular gap 36 is allowed to harden. The liner 22 made up of now hardened grout 20 can now improve anchorage performance in a similar way the
substrate dust 66 did before, so that the hardened grout 20 located in the annular gap 36 can substitute or possibly even overcompensate the effect of the now missingsubstrate dust 66.
Claims (9)
- Method for temporarily releasing a screw anchorage, in which- a primary screw (10) having a thread (13) that is tappingly engaged in a mating thread (63) in an ungrouted hole (90) in a mineral substrate (6) is unscrewed and removed from the hole (90),- a retrofitting screw (30) is subsequently screwed into the hole (90), thereby forming an annular gap (36) between the retrofitting screw (30) and the substrate (6), and- hardenable grout (20) is placed in the annular gap (36), and the hardenable grout (20) is hardened in the annular gap (36).
- Method according to claim 1,
characterized in that
the retrofitting screw (30) and the primary screw (10) have same thread pitch and/or same thread core diameter. - Method according to any one of the preceding claims,
characterized in that
the retrofitting screw (30) is a used screw. - Method according to any one of the preceding claims,
characterized in that
the retrofitting screw (30) and the primary screw (10) are of the same type. - Method according to any one of the preceding claims,
characterized in that
the retrofitting screw (30) and the primary screw (10) are one and the same. - Method according to any one of the preceding claims,
characterized in that
when the retrofitting screw (30) is screwed into the hole (90), a thread (33) of the retrofitting screw (30) is screwed into the mating thread (63). - Method according to any one of the preceding claims,
characterized in that
a quantity (25) of hardenable grout (20) is placed in the hole (90) before the retrofitting screw (30) is screwed into the hole (90), and at least a fractional amount of this quantity (25) of hardenable grout (20) is subsequently placed in the annular gap (36). - Method according to any of the preceding claims,
characterized in that
the ratio of the outer diameter of the thread (13) of the primary screw (10) to the pitch of the thread (13) of the primary screw (10) is between 1 and 2. - Method according to any of the preceding claims,
characterized in that
the ratio of the outer diameter of the thread (33) of the retrofitting screw (30) to the pitch of the thread (33) of the retrofitting screw (30) is between 1 and 2.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP18187718.4A EP3608549A1 (en) | 2018-08-07 | 2018-08-07 | Method for temporarily releasing screw anchorage |
PCT/EP2019/070309 WO2020030459A1 (en) | 2018-08-07 | 2019-07-29 | Method for temporarily releasing screw anchorage |
Publications (3)
Publication Number | Publication Date |
---|---|
EP3833879A1 EP3833879A1 (en) | 2021-06-16 |
EP3833879B1 true EP3833879B1 (en) | 2023-06-14 |
EP3833879C0 EP3833879C0 (en) | 2023-06-14 |
Family
ID=63207540
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP18187718.4A Withdrawn EP3608549A1 (en) | 2018-08-07 | 2018-08-07 | Method for temporarily releasing screw anchorage |
EP19745144.6A Active EP3833879B1 (en) | 2018-08-07 | 2019-07-29 | Method for temporarily releasing screw anchorage |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP18187718.4A Withdrawn EP3608549A1 (en) | 2018-08-07 | 2018-08-07 | Method for temporarily releasing screw anchorage |
Country Status (4)
Country | Link |
---|---|
US (1) | US11828312B2 (en) |
EP (2) | EP3608549A1 (en) |
CA (1) | CA3103731A1 (en) |
WO (1) | WO2020030459A1 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20190292771A1 (en) * | 2018-03-23 | 2019-09-26 | Uwm Research Foundation, Inc. | Device and method for improving adhesive anchor performance |
EP4403782A1 (en) | 2023-01-17 | 2024-07-24 | Hilti Aktiengesellschaft | Screw anchor for a hybrid screw anchor system |
Family Cites Families (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4642964A (en) * | 1984-09-27 | 1987-02-17 | Kellison Roger C | Grout in place fastener system |
US5490365A (en) * | 1994-05-11 | 1996-02-13 | Roth; Steven A. | Anchor bolt assembly |
DE19510307A1 (en) | 1995-03-22 | 1996-09-26 | Hilti Ag | Mortar container for the chemical fastening of anchoring agents in boreholes |
US5895186A (en) * | 1996-10-07 | 1999-04-20 | Anthony C. Giannuzzi | Releasable barrier coating for chemical anchor bolt |
DE19820671A1 (en) | 1998-05-08 | 1999-11-11 | Fischer Artur Werke Gmbh | Self-tapping screw for use in solid building materials |
DE102009001815A1 (en) | 2009-03-24 | 2010-10-07 | Hilti Aktiengesellschaft | Method for anchoring a fastening element in a mineral component and fastening element for mineral components |
DE102011003127A1 (en) | 2011-01-25 | 2012-07-26 | Hilti Aktiengesellschaft | Fastening set for fastening attachment part to concrete, has mechanical anchor e.g. concrete screw and bolt anchor, arranged in drill hole, and corrodible cartridge comprising predetermined quantity of curable mass e.g. synthetic resin |
US9273714B2 (en) * | 2013-10-04 | 2016-03-01 | Fitzhugh Lee Jackson | System and method of installing and removing a temporary concrete barrier from a bridge deck |
EP2927512A1 (en) | 2014-04-01 | 2015-10-07 | HILTI Aktiengesellschaft | Fixing assembly with axially fixed mass presser plate |
EP3130811A1 (en) | 2015-08-12 | 2017-02-15 | HILTI Aktiengesellschaft | Screw driving-in method |
-
2018
- 2018-08-07 EP EP18187718.4A patent/EP3608549A1/en not_active Withdrawn
-
2019
- 2019-07-29 WO PCT/EP2019/070309 patent/WO2020030459A1/en unknown
- 2019-07-29 US US17/266,506 patent/US11828312B2/en active Active
- 2019-07-29 EP EP19745144.6A patent/EP3833879B1/en active Active
- 2019-07-29 CA CA3103731A patent/CA3103731A1/en active Pending
Also Published As
Publication number | Publication date |
---|---|
US11828312B2 (en) | 2023-11-28 |
US20210301853A1 (en) | 2021-09-30 |
WO2020030459A1 (en) | 2020-02-13 |
CA3103731A1 (en) | 2020-02-13 |
EP3833879A1 (en) | 2021-06-16 |
EP3608549A1 (en) | 2020-02-12 |
EP3833879C0 (en) | 2023-06-14 |
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